I definitely think that this is the best Solr book available at the moment. I would thus recommend this book.
There are some annoying things though. For example, they use the MusicBrainz database as an example throughout the book, but if you set up your own MusicBrainz SQL database to try the scripts in the example code, you will find that the SQL queries are made for an old version of the MusicBrainz database schema, so they won't work out of the box. They do include sample data in CSV format though, so most of the examples work.